In striking or musical timepieces, particularly minute-repeater watches, vibroacoustic improvements essentially concern the external elements allowing the sound level of the striking-work to be increased, but also the regulating elements, to limit the noise of the mechanism when the striking-work is released and thus to increase the emergence of sound produced by the striking-work, by increasing the ratio between the sound level of the striking-work and that of the noise of the mechanism.
As regards the external elements, radiating crystals or disassociated bezels can optimise the vibrational response of the external elements over a wide frequency band and thereby increase the sound level produced by the radiation of said elements. In order to have a high radiating power over a wide frequency band, the elements must be capable of vibrating freely, and independently of the excitation frequency to which they are subjected.
The vibrational amplitude of the external elements depends on good frequency tuning between the excitation frequency and that of the external elements, but also on good structure-borne sound transfer between the vibration generating element, such as a gong or similar, and a radiating element, such as a bezel/crystal assembly or a case back. The vibrations must therefore propagate easily without being attenuated by intermediate elements between the vibration generating element and the element intended to radiate, or by gaskets required for sealing the timepiece, which may prevent the radiating elements from vibrating freely.
CH Patent 698742B1 in the name of RICHEMONT discloses a device for connecting a striking-work gong to the crystal of a timepiece. The gong is integral with a heel portion secured by a screw to a part of the movement. This screw extends beyond the dial and rests via its end surface on the underside of an annular segment of an annular resilient component integral with the crystal. This annular resilient component has at least four annular segments, each having a rectilinear shape, seen in cross-section. The outer edge of the annular resilient component is intended to be clamped between a bezel and the middle of the timepiece case by means of a sealing gasket. The portion of the annular resilient component that is not underneath the crystal is housed entirely underneath the bezel.
EP Patent Application 2328044A1 in the name of ROLEX discloses a watch case comprising a middle part having at least one opening closed by a bezel and/or a crystal, or by a back cover. At least one of the elements closing the opening is connected to the case middle by a resilient metal member in the form of a ring or endless frame of hollowed cross-section, defined by the profile of a non-rectilinear wall, whose ends are joined to the periphery of the closure element, or respectively of the case middle. The profile of this non-rectilinear wall forms at least one annular fold of parallel orientation to the plane of the opening, this fold being produced by a curvature whose arc describes an angle comprised between 90° and 180°, to allow the closure element freedom of movement with respect to the plane of the opening.